Diabetes is a major risk factor for atherosclerosis. Atherogenesis involves endothelial dysfunction, activation and injury, inflammation, and smooth muscle cell migration and proliferation. Platelet activation in the narrowed arteries is the most proximate event in the culmination of an acute event such as acute myocardial infraction and stroke. Hyperglycemia is associated with all these adverse events in the process of genesis of atherosclerosis. The effect of diabetes (hyperglycemia) is mediated in large part by the state of enhanced oxidative stress, which is not counter-balanced by endogenous antioxidants. This paper reviews the ignition of oxidative stress in diabetes and the mediation of events leading to atherogenesis.